It is frequently necessary in laboratories in research and development and in production to introduce liquid amounts that can originate from different sources such as from liquid chromatographs into containers such as test tubes, microtiter plates, bottles, and the like, preferably in an automated manner, and also to remove such liquid amounts from then again in an automated manner. Liquid handling apparatus or liquid handling systems are used for this purpose.
The applicant inter alia manufactures liquid handling apparatus, so-called fraction collectors, for liquid chromatography in which the fractions resulting from the liquid chromatography are distributed in an automated manner in accordance with their creation and thus their chemical composition over different sample vessels that are preferably provided in the form of arrays in racks in the fraction collector. The sample vessels are positioned via these racks in at least one substantially horizontal plane in the fraction collector such that the individual sample vessels are traveled to by an output head and can be charged with the corresponding fraction. The traveling to the sample vessels takes place in a horizontal plane that is spanned by an X axis and by a Y axis standing perpendicular to the X axis and that is in parallel with the plane of the rack located in the fraction collector. The output head can then travel down in a vertical direction, i.e. in the Z axis, so that a tube that is arranged therein and that is connected to the liquid chromatograph via a hose travels into the corresponding sample vessel and introduces the fraction into it.
The positioning of the output head takes place via an X slide which is travelable in the direction of the X axis and at which an arm having a Y slide travelable in the direction of the Y axis is provided. A Z slide having the output head and travelable in the Z axis is arranged at this Y slide. The output head can thus travel to or into every sample vessel arranged in the plane spanned by the X axis and the Y axis.
The drive of the X slide takes place by an X drive motor via an X force transmission means in the form of a toothed belt and the drive of the Y slide takes place by a Y drive motor for driving the Y slide via a Y transmission means that can be a toothed belt or also a rotating spindle. The X drive motor is in a fixed position, whereas the Y drive motor is arranged at the Y slide taken along at the X axis and is moved along with it. The X drive motor together with the X force transmission means and the associated slide together with required guides, data and power cables as well as the Y drive motor with its data and power cables are accommodated in a parallelepiped-shaped housing that is generally located at the rear side of the liquid handling apparatus. Such an apparatus is e.g. known from EP 1 533 073 B1.
It has been found that this type of liquid handling apparatus such as is used for liquid chromatography can also be used in other sectors such as in preparative liquid handling systems in which liquids, that are also gel-like or pasty, but ultimately flowable substances, in the sense of the invention, can be introduced into containers from different sources, can be added in a metered manner, can be mixed in containers, and con be partly or completely removed from containers.
This extension of the application sector of the liquid handling apparatus has in the past already had the result that it has become necessary to adapt the dimensions of such an apparatus in a customized or application-specific manner. The applicant has previously designed its liquid handling apparatus as extensible in the direction of all axes for this purpose. Respective intermediate elements are for this purpose arranged in regions of the frame of the apparatus in which no drive components or the like are provided so then only extended guide rails and toothed belts or threaded spindles additionally have to be installed. It is also necessary to adapt the power and data lines of the Y drive motor taken along at the X slide to the changed dimensions. The longer the X axis is, the longer the power and data lines for the Y drive motor have to be. Apart from the fact that the taking along of the Y drive motor at the X slide has a disadvantageous effect on the dynamic behavior of the X slide, i.e. as a result of the increased mass of the X slide due to the Y drive motor, greater forces have to be exerted to accelerate and decelerate the X slide, provision must also be made that the power and data lines for the Y drive motor taken along by the X slide in particular do not impede other drive components in the construction space of the housing parallelepiped in the regions of the end positions of the X slide.
DE 39 26 670 A1 discloses a handling device having three fixed-position motors for moving a gripper in three spatial directions X, Y and Z. The drive of each axis takes place independently of the drive of the other axes via a belt drive for each axis. A decoupling of the movement of the Y and Z axes from the movement of the X axis takes place in that the motors of the Y and X axes drive their respective toothed belts via a square shaft that extends through the arm A so that the drive of the Y and Z axes can take place in the X direction independently of the position of the arm.
DE 42 00 923 A1 describes a biaxial linear drive in which fixed-position motors for the X and Y axes are provided. The movements of the X and Y axes are decoupled from one another. This is achieved in the same manner as in DE 39 26 670 A1 in that a first slide that travels in the X direction is displaceably supported in the X direction on a drive shaft that is provided for driving the slide in the Y direction.
DE 691 12 519 T2 describes a manipulator in which two fixed-position motors are provided, with the motor displacing a slide provided for the motion in the X direction via a ball screw in the X direction. The displacement of the manipulator in the Y direction takes place via a toothed belt that works in a manner released from the movement in the X direction.
US 2008/0064543 A1 relates to an apparatus having a triaxial drive for use inter alia in an automatic analysis apparatus. All the slides are driven in the three spatial directions via fixed-position motors. A belt drive is used for all the axes.
US 2009/0155039 A1 relates to a multiaxial robot. The drive of the tool carrier in the X and Y directions takes place only via belt drives, with an H-shaped extent of the belts being provided. The displacement of the tool in the X and Y directions takes place via an interplay of the rotational movements of pulleys so that a superposition of the X and Y movements is present.
WO 96/37346 discloses an apparatus for moving a working element in the X and Y directions. Its basic design corresponds to the H-shaped design described in connection with US 2009/0155039 having fixed-position drive motors and drive belts that run both in the X and in the Y directions.
WO 97/02931 discloses an apparatus comparable with the apparatus disclosed in WO 96/37346 A1 and US 2009/0155039. The basic design and the operating principle are the same.
It is therefore the underlying object of the invention to improve the drive for the Y slide.